The invention disclosed herein is a device for achieving controlled watering and fertilizing of plants, especially potted plants. Most persons who own potted house plants have no way of gaging the proper rate of fertilizing and watering them. Hence, it is not uncommon for plants tended by other than professional florists to exhibit poor flowering, growth and color and shriveled and unhealthy leaves. Death of a costly plant is often the consequence of over or under watering and fertilizing.
There is a commercially available device which is used in conjunction with potted plants and is intended to provide regulated feeding and watering. This device comprises a soft felt ring having a hole through its center. In a commercially available model the ring has a diameter of about 8.5 cm, a thickness of about 2 cm and a hole of about 3.5 cm. The ring is deposited in a leak-proof pan or reservoir in which the potted plant is normally placed. A water impervious plastic cup containing fertilizer is placed in the hole inverted, that is, with its plastic bottom up and its top down. What is normally the top opening of the cup has a thin porous disk of non-woven material glued onto it so the enclosed grains of fertilizer do not spill out when the cup is inverted and so water can enter the cup and dissolved fertilizer can issue from it. There is a pin hole in the upwardly presented bottom of the plastic cup to relieve entrapped air so water can rise into the fertilizer through the porous disk. The felt disk is covered with water and must be kept covered for the life of the fertilizing device. The pot containing the plant is placed on the felt ring with the expectation that the roots of the plant will tend to grow toward the source of the dissolved fertilizer which is supposed to diffuse into the soil through the hole in the bottom of the pot.
The known device has some disadvantages. The felt ring is not as durable as one would desire in the chemical fertilizer environment. The flow path of the fertilizer solution out of the cup to the bottom of the plant pot is devious and opposed to the path that fresh water flows into the cup. Because the inverted cup is impermeable plastic, the fertilizer solution must migrate radially outwardly along the bottom of the felt ring and into and up and around the ring into the water around the ring to get to the bottom of the pot. The felt is a poor conductor of liquid by capillarity which must be relied on to get the fertilizer solution to the bottom of the plant at the desired rate. The felt, which must have low density and low rigidity to be saturable, becomes soft and does not support the pot in a completely stable manner. The arrangement is such that apparently the felt itself could absorb and hold a substantial percentage of the fertilizer. The pin hole can become plugged. If it plugs by calcification or other cause and the water depletes, the next time water is added an air trap might be created in the cup which could inhibit outflow of fertilizer.